1. Field of the Invention
This invention relates to production of color print film and, more particularly, to the use of digital imaging in the dye transfer process of color film printing.
2. Prior Art
Early color motion picture prints were made by depositing dyes on black and white film by timing individual frames by hand. Later, many alternative dye chemistries and mechanical methods of application were developed and evaluated by the industry. The dye transfer, or imbibition (IB) process, emerged as the preferred technology in color motion picture printing until around 1970, but was eventually displaced (starting in the 1950's) by the process of color-coupled development of dye intermediates incorporated in the film during manufacture.
In the dye transfer process, a colored image is formed when cyan, magenta and yellow dyes are transferred to blank stock from three different black and white positive separations made on matrix film. The image on matrix film exists in the form of a gelatin relief, consisting of a 3-dimensional topography of hills and valleys, the relief (or thickness) of which is proportional to image density. During the printing procedure, the matrix film is soaked in dye, rinsed to remove surface concentrations, and brought into registered contact with a mordanted blank. The dye diffuses from the matrix film into the blank to form a positive image; a colored picture appears after the third dye is transferred from its matrix film to the blank. In motion picture prints, the sound track and other coding marks can either be primed with dye or primed separately by other means, including means to provide a silver record.
Dye transfer prints have always been held in high regard in both the motion picture and still photography fields for their dynamic range, color gamut, and archival nature. Some of these advantages, compared to those of color-coupled film, are inherent in the materials and processing used to make a dye print. A review of the preparation of gelatinous film reliefs or "matrix film" and their use in the dye transfer method of producing print film is presented by Troland in British Patent 410,733. Goldberg et al., in U.S. Pat. No. 2,870,704, discuss the production of gelatin relief matrices for color printing. Other historically important patents relating to dye transfer printing using matrix film include U.S. Pat. Nos. 1,535,700; 1,900,140; 728,310; 2,044,864 and 2,930,691. British patent BP 187,638 provides a thorough treatise on dye transfer from start to finish.
A disadvantage of conventional dye transfer or IB printing is the difficulty and lack of flexibility in controlling color rendition. A system for producing color prim film which overcomes the above disadvantages and provides flexibility with respect to choice of matrix film, exposure, development, blank stock, mordant, dyes, transfer chemistry, and transfer equipment is desirable.